Asked about last weekend’s four-hour golf game with President Obama on Martha’s Vineyard, Bloomberg told reporters yesterday, “The economy was the main subject, other than discussing golf.”

Now there are whispers that the president went even further and sounded out Bloomberg about whether he would join his foundering economic team as treasury secretary, replacing prime blame-target Timothy Geithner.

“Obama needs Bloomberg more than Bloomberg needs Obama,” a source tells us. “Obama’s looking to do something bold and credible before the election.”

Insiders say multibillionaire Bloomberg, who was on the short list for the gig in 2008, has the star power and credibililty to help Obama. “It’s been the focus of a lot of discussion,” said one Democrat. “He’s very well-liked and well-respected on Wall Street.”

Because Bloomberg has lately been giving speeches on national issues in key states such as Iowa and New Hampshire — and behaving like a possible independent presidential candidate for 2012 — Obama has even more reason to bring him into the fold.

“Bloomberg would absolutely devastate Obama in states like Florida and New York,” said our Dem. “Bloomberg couldn’t win, but he could definitely elect a Republican president” by siphoning votes from Obama.

Even more, a move to Washington would be a package deal for the mayor. His girlfriend, Diana Taylor, a former New York state banking superintendent, has been eyeing the Federal Deposit Insurance Corp. chair since 2006, when it was rumored that the National Rifle Association scuttled her chances because of Bloomberg’s anti-gun stance. Current FDIC chair Sheila Bair‘s term will be up next year.

“It’s the proverbial cherry on the sundae,” a source says. “It’s all kind of pieced together.” Reps for the White House and City Hall denied any job discussions.